Fluid cartridges are subassemblies to be exchanged with a corresponding fluid ejection assembly. A common fluid cartridge is an ink cartridge. A common fluid ejection assembly is a printer. In general, two types of ink cartridges can be distinguished. A first type consists of an integrated print head cartridge, wherein the cartridge comprises a print head. A second type consists of an individual ink container. An ink cartridge is connected to a receiving structure of a printer. The receiving structure and the ink cartridges are provided with the proper interfaces for guiding ink from the cartridge to the print head for printing. In addition to the ink interface, an air interface, a keying interface, an electrical interface and an alignment interface can be provided in the ink cartridge and its receiving structure. The air interface transports air to and from the cartridge, mostly for pressure control inside the cartridge. The keying interface ensures that the respective cartridge is seated in the proper ink cartridge receiving structure. The alignment interface ensures that the interfaces are well aligned for connection. The electrical interface sends electrical signals between a printer control circuit and the ink cartridge. The signals may relate to ink cartridge characteristics.
An extra lock is usually provided to maintain substantially air and liquid tight connections between the cartridge and the receiving structure. The extra lock should also maintain the electrical connection. A known locking technique involves the use of a bail to keep the cartridge sealed to the receiving bay. Another known locking technique uses a deforming snap finger that engages a notch to keep the cartridge sealed.
The known lock mechanisms tend to consume a relatively large amount of space within the printer. In addition, significant force may be needed to establish the lock. In some cases, the cartridge is inserted in an inclined orientation, after which it is rotated back to normal position to make the interfaces engage. This usually involves deflection of engaging elements so that improper interface connections, leakage, and material wear or damage are likely to occur.